Nope. It's a Reg./Order thing. It begins with what *privileges* each rating gives a pilot but is complicated by what *procedures* are availabe to be used in operations ie PVT, AWK & CHTR.
A NVFR rating is *only* available for the pilot to use on PVT & AWK operations.
NVFR procedures can be used for PVT, AWK & CHTR however, in the CHTR case, the pilot & aircraft must be capable of using IFR procedures. That means the pilot must be instrument rated and the aircraft must have the necessary equipment for IFR flight.
So, how does a pilot with an instrument rating allowing flight under IFR procedures use NVFR procedures?
A pilot who holds a current instrument rating *and* meets the specified experience requirements for NVFR flight is granted the privilege of using NVFR procedures. The catch is that the pilot must hold an instrument rating. Lose the instrument rating = lose all NVFR privileges (unless you hold some othe rating that allows some amount of NVFR procedures. Hmm....NVFR or Night Ag. ratings anyone?)
BTW, twenty years ago CASA/CAA/DoA/DCA/whatever-this-year used to automatically remove the SEAO restriction from a NVFR rating as part of the issue of a M/E CIR.